The ability to change the output frequency and/or scan a selected range of frequencies in variable step sizes is essential to many types of test equipment, spectrum analyzers, signal generators and other devices using frequency synthesizers. In prior art structures it is generally common to provide a switch for incrementing (increasing the frequency in steps), a switch for decrementing (decreasing the output frequency in steps), a switch for selecting the size of the frequency step change and a rate switch which controls the number of steps per second that the frequency is changed. Generally, all of these switches provide the operator with versatility but require considerable attention, and in many instances both hands, in the use thereof.